Strategies for industrial noise control In a chemical plant with high noise levels, which combination is recognised as the comprehensive control strategy?

Introduction / Context:
Industrial noise management follows a hierarchy of controls to ensure regulatory compliance and worker safety. Because plant noise often arises from multiple equipment items and pathways, an effective programme rarely relies on a single measure. Instead, source controls, path (transmission) controls, and receiver protection act together to deliver sustained reductions.

Given Data / Assumptions:

• Multiple rotating machines (fans, compressors), process valves, and piping contribute to noise.
• Occupational exposure limits apply over an 8-hour shift.
• Objective: practical, maintainable noise reduction.

Concept / Approach:
The “three-pronged” strategy includes: (1) source control (quieter equipment selection, balance/alignment, anti-cavitation trims, vibration isolation, silencers on intakes/exhausts); (2) path control (enclosures, acoustic barriers, duct liners, lagging, break-out noise reduction, room acoustic treatment); and (3) receiver protection (hearing protection devices, exposure time management, quiet zones). Applying all three provides robust reductions and accommodates operational constraints.

Step-by-Step Solution:

Verification / Alternative check:
Case studies show that combining a modest source reduction with a modest transmission reduction often outperforms either alone and can avoid costly over-design at a single point.

Why Other Options Are Wrong:

• Any “only” option ignores the complementary nature of controls and typically fails to achieve targets across all work areas.
• Administrative controls only: Helpful but insufficient without engineering measures.

Common Pitfalls:
Overreliance on hearing protection without addressing sources; neglecting maintenance-induced noise increases (bearing wear, misalignment) after initial success.

Final Answer:
All (a), (b) & (c)